~아/어서

This is one of the most common grammar patterns in Korean. It connects a reason (first clause) with a result (second clause).

How to attach it:

• If the last vowel of the stem is ㅏ or ㅗ, use ~아서.

  • 가다 → 가서
  • 오다 → 와서

• For all other vowels, use ~어서.

  • 먹다 → 먹어서
  • 피곤하다 → 피곤해서

• 하다 verbs always become 해서.

Important: You cannot use past tense (~았/었) in the first clause with ~아/어서. The tense is determined by the second clause only.

Tip: 만나서 반갑습니다 is a set phrase — you’ll hear it every time you meet someone new.